Pole and guy calculator



Dec. 28, 1937. w, w MAYFlELD 2,103,332

POLE AND GUY CALCULATOR Filed Aug. 11, 1936 2 Sheets-Sheet l v POLE GUYCALCULATOR OVERHEAD LEAD IN FEET 15 m 8 1 6 IO 16mm FEET 11 9. 5. v 3 a;X *my INVENTQR. Wa/rer W Mayf/e/d ATTORNEY.

Dec. 28, 1937. w. w. MAYFIELD POLE AND GUY CALCULATOR Filed Aug. 11,1936 2 Sheets-Sheet 2 c uxmmgo LIN FEE \J POLE. seuv l0 CALCULATOR 51? aIN V EN TOR. W4 her 1 11 Mayflk/a A TTORNE Y.

Patented maze, 1937' UNITED STATES PATENT OFFICE 3 Claims.

' pole line construction, guying of stacks, and the like.

In the construction of pole lines carrying telephone, telegraph or powertransmission wires, it is important that certain constants of the linebe accurately calculated so as to insure that the line, whenconstructed, will be strong enough to withstand conditions encountered.Heretofore the data used in such computations have been available intable or chart form, which at best are somewhat cumbersome to use. Thefactors to be considered in the calculations vary through such widelimits, because of the conditions encountered along the line, that it isfre- 'quently desirable to make calculations at the site of theconstruction of the line. This has been inconvenient heretofore becausetables and charts do not lend themselves well to use in the field, and,as a result, calculations have been made in the office, and allowancemade for factors not definitely known. 1

It is an object of the present invention to provide a simple and cheapcalculating device which can be carried in the pocket for use in thefield and which is constructed to facilitate calculation of the datarequired for the construction of a pole line or the like.

Another object of the invention resides in the provision of scales uponthe calculating device upon which all measurements taken to determinethe data required for the construction of a line may be read directlywithout computations other than those made by the calculating device.

Further objects of the invention, not specifically mentioned here, willbe apparent from the detailed description and claims which follow,reference being had to the accompanying drawings in which a preferredembodiment of the invention is shown by way of example, and in which:

Figure 1 is a plan view of the calculator;

Figure 2 is a detailed plan view of the base member of the device;

Figure 3 is a detailed plan view of the intermediate member;

Figure 4 is a detailed plan view of the top member; and

Figure 5 is a cross sectional view through the device, takensubstantially along the line 5-5 of Figure 1.

The calculating device shown by way of example, is constructed forcomputing the sizes of guy wires. needed to brace a pole line, and todetermine the minimum class of pole needed therefor under varyingconditions. As shown, the device consists of three members, a base I, anintermediate member 2, and an upper member I, which members are heldtogether by an eyelet 4 that serves as a pivot to permit the members tobe rotated with respect to each other. Preferably the members arecomposed of material that is thick enough to be fairly rigid.

Upon the base member I there is provided a scale 5 designated as Heightin feet. This scale indicates the vertical height in feet of the pointof attachment of the guy wire to the pole, which can be measured byordinary methods. Scale 5 is located upon an are centered at the centerof the pivot 4, and having a radius the same as the radius of the uppermember 3. Scale 5 is a logarithmic scale starting from a unity pointthat is located upon a diameter 5a, and progressing so that the value iis located 90 degrees from the starting point. That is the scale is laidout with a logarithmic cycle covering 90 degrees. Scale is extendedthrough 1.7 cycles to indicate heights up to 70 feet, the maximum heightlikely to be encountered in pole line construction.

The base i also carries a scale 6 which is graduated to denote thefigure by which the tension of the wires or conductors are to bemultiplied for a given ratio of lead to height. Lead of the guy wire isthe term commonly used in the art to designate the distance from thepole to the point of entry of the guy into the ground. The ratio, leaddivided by height, represents the tangent of the angle of the guy. Tolocate scale 6 with respect to scale 5, an angle of 45 degrees isassumed. The tangent of this angle is 1, and the reciprocal of thetangent is also 1. The reciprocal of the sine of the angle of 45 degreeswhich is the cosecant is found to be 1.414, and this value is locatedupon scale 6 opposite the unity point upon scale 5. Other points uponthe scale 6 are located in a similar manner, scale 5 being extended pastthe base line and point 1 thereon for construction purposes, thisextension being subsequently erased. Scale 6 need be extended only toinclude ratios as low as 1.05, for when the ratio of lead divided byheight is less than 1.05, the scale is not needed, as will hereinafterappear. Scale 6 may be designated as the K scale.

The base member i is also provided with a scale 9 that is graduated inpounds pull. This scale is a logarithmic scale, increasing from 1000 to10,000 in a, 90 degree arc, and extending up to 30,000 pounds. The 1000mark on scale 9 is located 39 degrees from the base line through unityon scale 5, this location being chosen for convenience. The radius ofthe are upon which scale 9 is located is greater than the radius of theare upon which scale 5 is located, so that scale 9 lies beyond the edgeof upper member 3.

For convenience in reading thedevice, the base I also carries scales 8which are graduated in B. & S. gauge copper wire, and represent thepounds pull of the wire when stressed to one half the ultimate strengthof the material. Scales 8 are located with respect to scale 9 in thefollowing manner. From tables it is determined that a #2 B. 8: S. harddrawn copper wire has an ultimate strength of 3000 pounds. The NationalSafety code specifies that under certain conditions electric light andpower wires shall not be stressed to more than 50% of the ultimatestrength, so of the ultimate strength is taken,

that is 1500 pounds. A straight edge is laid through the center ofmember i and the 1500 mark on scale 9, and the inner #2 mark on scale 8is located along this edge. This determines the scale pointcorresponding to the pull in pounds of a single #2 wire stressed 50%.The scale is moved around the center to the 3000 mark on scale 9 tolocate the #2 mark on scale 8 corresponding to two #2 wires eachstressed to 50%, then to the 4500 mark on scale 5 to locate the point onscale 8 corresponding to 3 wires, then to the 6000 mark on scale 9 tolocate the point on scale 8 corresponding to 4 wires. This operation isrepeated for the other sizes of wires. Thus scale 8 is formed to readpounds pull of the wires directly by setting the device tothe desiredpoint on the scale, and no calculations are necessary.

The base member I is also provided with a scale 7 located outside ofscale 8 and graduated to indicate effective pull, in pounds, due to windaction upon wires of the sizes indicated. This force tends to overturnthe poles, and the scale I is useful in determining the size of pole tobe used as well as to determine the strengths of storm guys. This scaleis located with respect to scale 9 so that 1.00 on scale i lies on aradius from the center through the 1000 mark on scale 9. Scale irepresents in pounds, the values of scale 9 divided by 1000. From tablesit is found that the transverse force on stranded triple braidedweatherproof wire is 1.08 pounds per linear foot,- so the point on scalei is located by extending the radius on which 1080 pounds is indicatedon scale 9 through scale l. The other points on scale 'I are located inthe same manner. The intermediate member 2 is generally circular inshape and of a diameter such that its circumference falls just insidescale 6, when the members are together as described above. An ear or tabextends radially from the member and is long enough to overlie thescales 8. This ear carries a scale l located along the left hand edgethereof, Figure 3, indicating the number of soft drawn copper wires, anda scale It along the right hand edge indicating the number of hard drawncopper wires. The scales l5 and l6 c0- operate with scale 8, as willpresently appear. The edges of the ear or tab are formed as radiicentered uponthe center of the member and are 20 degrees apart. Themember 2 also carries a scale 13 located at the edge of the circularportion thereof. This scale is a logarithmic scale having .a 90 degreecycle. The 1000 point on the scale is located on the median line of theear, that is 10 degrees from aioaesa the edge indicating hard drawnwires. The scale 13 is extended for one cycle below 1000 and two cyclesabove, a total of 3 cycles or 270 degrees, this span being necessary tocover the required range. Scale 13 indicates size of guy wire in termsof the pounds pull it will withstand.

The member 2 also has a scale I4 located within the scale i3 andgraduated in terms of minimum class of poles. This scale is determinedfrom tables giving the maximum strength that a class of pole willwithstand and projecting that value from scale l3. As indicated on thescale, the stronger the pole, the lower its class number.

The upper member 3 is circular, and is provided with an opening orwindow [8 that overlies the scale I4, so that that scale may be viewedtherethrough. The legend minimum class of pole is located adjacent tothis opening, with an arrow pointing along the line on which the scale Mis to be read.

The member 3 is also provided with an opening or window through whichthe K scale 6 on the base member may be read. An index arrow marks theline upon which the reading is to be taken, and there is a second arrowin line therewith and at the periphery of the disk, for a purpose thatwill be later noted.

The member 3 is provided with a series of openings or windows 20, 2!,22, 23, and Ill, formed to overlie scale IS on member 2, to permit thatscale to be read therethrough. A single window would serve the samepurpose as this'group of openirgs, the solid separators between thewindows being left to support the outer rim portion of the disk. Themember 3 might be made of a transparent material, in which case a singlewindow would replace this group of openings.

The scales Hi, i i and it are located upon the member 3 in the followingmanner. A base line is drawn through the index arrow and serves as aunity point upon the scale i0. This scale gives the lead of the guy wirein feet, that is the distance from the pole to the point where the guyenters the ground. The scale is logarithmic, covering a cycle in 90degrees, and extended through two full cycles, so that leads up to 100feet may be read upon it.

The scale i i, which gives pull of the guy in feet, is located upon theupper half of the member 3, within the inner edges of the windows. Thepull in feet is determined by measuring down the line 100 feet in eachdirection from the pole to be guyed, connecting these points with astraight line, and measuring the vertical distance in feet from the poleto this connecting line.

The 50 point on scale ii is located 49 degrees above the base linethrough the index arrow. The scale is constructed from this point as alogarithmic scale covering a cycle in 90 degrees. From the tabulateddata it is known that a lead of 50 feet is the equivalent of a dead end,with unity safety factor. The point on scale ll corresponding to '75 ismarked Dead end, safety factor 1 by suitable abbreviation, and the 100mark on the scale is marked the same with a safety factor of 2.

The scale I2 is located on the opposite side of the windows from scaleII, and is graduated in degrees of line deflection. rived from theformula,

8 $1116 /a of angle of deflection.

This scale is deamass:

is therefore in line with the point on scale II.

The calculating device thus constructed is used in the following manner.Assuming that two strands of #2 hard drawn wire are to be guyed, thatthe height of the point of attachment of the guy to the pole is 50 feetand that the lead of the guy is 20 feet, and that the pull of the guy is50 feet, that is a dead end. The member 2 is turned to line the righthand edge of the car so as to bring the scale point 2 on scale l6 intoalinement with the scale point 2 in the second row of scale 8. Themember 3 is then turned so as to bring the point 20 on scale I intoregistration with point 50 on scale 5. The constant K for thiscombination of lead and height is read from scale 6' through window l9opposite the index arrow, and is 2.7. The member 3 is turned to alinethe outer index arrow with the 2.7 mark on the scale 5. The size of guywire required may then be read on scale l3 opposite the 50 mark on scaleH, and will be 8100, the proper size of guy wire for the aboveconditions with a safety factor of 1. If the problem is changed byincreasing the safety factor to 2, the size of guy wire will be readopposite the arrow designated as "D. E.S. F. =2, indicating Dead andsafety factor 2. If the angle of deflection of the line is less than adead end, say having a pull in feet of 30, the size of guy wire requiredwill be read opposite point 30 on scale ll.

Assume that in the example stated above it is necessary to run the guywire to a stub pole, as would be the case where a street or obstructionprevents guying the pole directly to the ground. The ratio of height tolead will be small and the outer arrow on the member 3 is turned to thearrow marked Overhead" on member I. The size of guy wire then requiredwill be read opposite the 50 point on scale II as before, and will be3000.

The calculator may be used to determine the minimum class of polerequired under American Standards Association ruling, in the followingmanner. Assume the pole is to support three #4/0 bare copper wires witha front span and a back span each of 250 feet and it is desired to knowthe minimum class of pole that will be required to withstand 8 pounds ofwind per square foot on the wires when covered with an inch of 108.

The right hand edge of the ear on member 2 is set at 4/0 on scale 1. Themember 3 is turned to aline the index arrow with Overhead point on scale5. The middle and rear members are held while the front member is turnedto 2.5 (250 feet span) on scale 5. The front and middle members, 2 and 3are held together and moved until the index arrow is again at Overhead.The members I and 2 are held, and the member 3 is again moved to alinethe index arrow at 3 (number of wires) on scale 5. With this setting,

the minimum class of pole required will be indicated through the windowIS on scale l4 opposite the arrow. A class 7 pole is indicated. If it isdesired to know the force in pounds on the wires, under the conditionsassumed, this may be read on the scale I3 opposite the arrow at 5 on thescale II, and will be 750 pounds.

Other types of problems arising out of other conditions can be solvedreadily with the calculator in substantially the same manner asindicated in the above example as is obvious from the above description.

While I have chosen to show the invention in connection with guycalculations for copper wire, it will be apparent that scale 8 canreadily be modified to adapt the calculator to other types of wire, suchas aluminum, iron and steel, and the scale may be further modified toshow loading constants other than the 50% of ultimate strength shown.

As was previously explained, the edges of the ear or tab on the member 2are radii located 20 degrees apart, that is, each is 10 degrees from thecenter line of the ear. The 1000 pound mark on the scale 9 was noted asbeing 39 degrees from the unity point on scale 5, and the dead endposition 50 on scale H was noted as being 49 degrees from the indexarrow on member 3. The offset of the straight edges of the ear istherefore equal to the difference between the angles of offset of thescales with which the readings that are taken along these edges arecombined, and the accuracy of the calculator is assured.

The one edge of the ear is used for hard drawn copper wires and theother edge is used for soft drawn copper wires. Soft drawn wires have aworking strength of but of the working strength of hard drawn wires.With the arrangement shown, soft drawn wire calculations are equally asaccurate as are the hard drawn calculators.

From the foregoing it will be apparent that I have provided a new andimproved calculating device that is possessed of many advantages. Thedate required for computation with device is simple data that may beacquired by direct measurement and without computation. By simplemanipulation of the device the computation of that data is accomplishedand the results read directly from the various scales on the device. Thecomputator is simple and rugged and may be carried about without dangerof destruction.

While I have shown my invention by illustrating and describing apreferred embodiment of it, I have done so by way of example, and am notto be limited thereby, as there are many modifications and adaptationsthat can be made by one skilled in the art, within the teachings of theinvention.

What I consider new and desire to have protected by Letters Patent is:

1. A calculating device comprising a base member provided near its edgewith a scale, an intermediate member movable with respect to said baseand having a set of graduations thereon, an ear on said intermediatemember, a set of graduations on said ear adapted to cooperate with saidfirst scale, a set of logarithmic graduations on said base member, asecond set of logarithmic graduations on said base member disposedconcentrically within said first set, an upper member movable withrespect to said base and intermediate member there being windows in saidupper member through which are visible the set of graduations on saidbase member, a logarithmic scale on said upper member, cooperating withthe first one of said graduations on said base, and a second logarithmicscale on said upper member cooperating with the graduations on saidintermediate member through said windows.

2. A calculating device comprising a base, a scale on said base, asecond scale on' the base opposite the first, a third scale on the basewithin the second. an intermediate member movable with respect to thebase, an ear on said intermediate member overlying said first scale, ascale on said intermediate member at the edge thereof,

a second scale on said intermediate member 7 within the first, an uppermember movable with respect to the other members, there being aplurality of windows in said upper member, a scale on' said upper membercooperating with the secand one of said scales on said base, an indexarrow on said upper member adapted to cooperate with the third one ofsaid scales on said base through one of said windows, a second indexarrow on said upper member adapted to cooperate with the second scale onsaid intermediate memher through anotherone of said windows, and a scaleon said upper member adapted to cooperate with the first scale on saidintermediate member through the others of said,windows. v

3. A device for calculating pole line data comprising a base member, anintermediate member, an upper member, means for pivotally fixing saidmembers together so that each may be rotated with respect to the basemember located concentrically of said pivot, said scales being graduatedto indicate pounds others, scales on said- Difll of wires, heights ofwires in feet above the ground. and cosecants oi the angles between guywire and pole, respectively; said intermediate member being circular andhaving a diameter equal to the a wires. pounds pull of transverse windson said intermediate member disposed within said first scale andgraduated in class of poles, said upper member being circular and havinga diameter equal to the diameter of said height of wires scale, andhaving at least a portion thereof through which said {size oispectively, may be viewed and index arrows on said upper member adjacentthe point throukh which said cosecant scale is visible.

guy wires scale, re-

